FSM432 MKIII doesn’t always switch when...

My FSM432 MKIII does not always switch when I click on the far right switch (I think that is the one for the up arrow). I am not in front of it right now. Is there anything I can do on my own to fix it?
I unscrewed the bottom cover and the switches have a spring in the middle. Hoping I can fix this on my own instead of buying a new footswitch.

Depends if it's a mechanical problem with the the switch or a hic-cup with the MIDI signal to the amp. You could try a factory reset of the FSM432 mkIII.....

"Power On" + TAP + Up = Factory reset of the FSM-432.
Press and hold TAP and Up until the display shows a double eight incl. decimal point. Then release the buttons. The individual segments of the display will
flash consecutively to indicate the successful factory reset.

It's also in the manual.

Hello,

I know this is a really late reply, but I removed the backplate on mine last week and cleaned it up with electronic cleaning spray.
However, for me it was the "B" button that was the issue. This fixed my issue.

This stomp switch issue is a perennial problem I promise you. I'm sick of changing out switches for some of my friends in their pedals. Oddly, the better system is the cheap Behringer type which have a tiny "tactile" switch mounted direct on the PCB and a soft rubber actuator which can give when the pedal is stepped on. Those switches cannot be put under too much pressure and seem to go on for ever. With decent soldering technique it isn't too difficult to change them either. Of course they are not changeover types, they simply make when pressed and break again when released so they need active circuitry in the pedal, usually FETs, to perform the switching action. Not everyone believes in that, (despite what engineering types like me would say). Your H&K amps have that very system set up inside to make some of the channel changes within the signal circuitry. Certainly sounds ok there to me!

I think some of this is down to the fact that there are tap dancers and there are clog dancers out there. You are either one or the other naturally, (no criticism of either intended), and that has to impact on the longevity of stomp switches in general. Of course if a clog dancer can take on a course of tap dance lessons and learn to be lighter on their feet it would help.

I haven't seen the inside of a FSM432, I've never actually had any reason to open my own up. I would imagine that a switch replacement should be a fairly standard task if you have soldering skills and a decent setup of tools but having said that... Don't suppose you took any pics while you were in there did you KC?

bordonbert wrote:Don't suppose you took any pics while you were in there did you KC?

Sorry to say, no I didn't. But it was super easy. Just remove the bottom plate. And you have two circuitboards. One smaller for the B, D and Tap buttons and one bigger for the rest. Plenty of space in there. You be in and out of it in less than five minutes Unless you wanna do some parts replacements. Then it might take you a little longer

Aha!  So the switches are mounted directly onto a couple of PCBs and not just wired to them?  If so that does mean dismantling to deal with a switch replacement.

Don't suppose you noticed what type of switches they use did you?  The usual modern stomp switch is a 3PDT type.  It has three switch wafers which changeover together on the stomp.  That means 9 pins to be desoldered from the PCB and that is a bit of a pain if they were a close fit in the board holes.  If they use a single SPDT three pin switch and circuitry on the PCB to deal with different functions it would be much easier to work on.




(Hahaha! Just seen your country of origin! Yes, I get "Metal Is My Religion" now. I've spent time on North Sea survey boats with your neighbours the Norwegians. It actually is a religion with you guys isn't it? )

bordonbert wrote:Aha!  So the switches are mounted directly onto a couple of PCBs and not just wired to them?  If so that does mean dismantling to deal with a switch replacement.

Don't suppose you noticed what type of switches they use did you?  The usual modern stomp switch is a 3PDT type.  It has three switch wafers which changeover together on the stomp.  That means 9 pins to be desoldered from the PCB and that is a bit of a pain if they were a close fit in the board holes.  If they use a single SPDT three pin switch and circuitry on the PCB to deal with different functions it would be much easier to work on.

There was two "pins" on the left and two pins on the right side of the small switches. The switch itself was not bigger than your ringfinger nail. A small black circular pad in the middle.
Not like a 3PDT. the switch is one part and the "stomper" is one part. And there was a small spring between them. A little bit hard to describe. I wish I had taken some photos. It didn't cross my mind. It will take you less than five minutes to take it apart to see for yourself what it looks like. It's a walk in the park Just flip it over, remove the screws and there you have it. Then a few screws on the "motherboard" and you can flip it over and see the switch itself.

GREAT!!! That was the system I wqas talking about. Those small switches with the black dot in the middle are the "tactile" type I mentioned. They are easy to remove and replace and they cost pence (or öre) to buy. That is good news. Thanks for that info it should be useful in the future. Once again H&K's good design philosophy shines through.

bordonbert wrote:GREAT!!!  That was the system I wqas talking about.  Those small switches with the black dot in the middle are the "tactile" type I mentioned.  They are easy to remove and replace and they cost pence (or öre) to buy. That is good news. Thanks for that info it should be useful in the future.  Once again H&K's good design philosophy shines through.

Glad I could help. It really is a breeze to open it up and get to the switches and other parts. Like I said, in less than five minutes you have taken it apart.
Lucky I only had to moister it up with some electric cleaning fluid, this time And I learned something to "tactile" switch Too bad I'm not good with the soldering iron hehe.